Reset circuit for electronic counters



a fhg 1. E. GRosDoFF RESET CIRCUIT FOR ELECTRONIC COUNTERS Filed Feb.25, 195o Sept. 25, 1951 (l/NTE WPI/r Y Patented- Sept. 25, 1951muri-:DpY STATES PATENT OFFICE vRESET CIRCUIT FOR ELECTRONIC COUNTERS ofDelaware Application February 25, 1950, Serial No. 146,354

4 Claims. (Cl. Z50-27) The present invention relates toy electroniccounting systems and. more particularly is an improved resetting systemfor electronic counter systems.

Electronic counting systems in general, use as abasis a chain or cascadeof trigger circuits each of which is capable of .assuming either of twoconditions of stability. `The basic trigger circuit with which thepresent invention is illustrated as being utilized is the triggercircuit of the general type described in Theory and Application ofVacuum Tubes by Herbert J. Reich, published in 1944. In one of itssimplest forms, this trigger circuit includes two triodes in which thegrid of the first triode is coupled to theanode of the Second triodethrough anetwork comprising a parallel connected resistor and capacitor,and the grid of the second triode is similarly coupled to the anodeofthe first triode through a similar coupling network. The cathodes ofboth triodes are grounded. f Grid and anode potentials areapplied to therespective electrodesthrough separate resistors. Y

In operation, if a negative Vvoltageis applied to the grid of the rsttriode, the anode current of the triode will be reduced and the anodepotential will become' more positive. vDueto. the connection through thecoupling resistor, the grid potential of the second triode will becomemore positive, causing an increase in the anode currentof the secondtriode, with a resultant decrease in the second triode anode potential.This decrease in anode potential wi11,in turn, cause the grid potentialof the rst triode to .become more negative. This action will continueuntil the anode current of the first triode is cut off. The rst triodewill remain cut off, and the second triode will remain conducting, untila negative potential is applied to the grid of the second triode. Thetubes operating conditions are thereby reversed and the first l"'generates a pulse which is appliedto -a third trigger circuit to causeit .to transfer conduction. As many trigger circuits as are requiredforobtaining a desired count may be used. By the use of feedv,backbetween trigger circuits, a `counter may complete a cycle of countingwith fewer applied pulses than are required without feedback.

Regardless of the feedback connections between trigger circuits, allcounter circuits, at the ,beginning of a count, usually have some-desired ""L'starting position with conduction in one `of the triodes ofeach trigger circuit. `Toattain this starting position at thetermination of a count,V

a resetting circuit is usuallyprovided. This con- .sists of a resetpulse source whichis connected to ""a grid of one of the triodes in.yeach of the trigger circuit usually generates pulses .which tend, to

drive the following trigger circuit and sometimes "-"do. This reset andsettling down period, or total reset time, `seriously aiects thespeedofthese types of counters. and .thus 4their, Aapplication in..

situations requiring. continuous rapid successions 4of counts isprevented or requires an alternate.

counter which can be switched on to allow time triodebecomes conductingandthe anode current i.

of the second triode is cut oi.

For the purposes of counting, a pulse is usually applied to the rsttrigger circuit in the chain to transfer conduction from one tube to theother. The next pulse, applied to the rst trigger circuit,

transfers conduction back to the rst tube andA atv the same time a pulseis generated by the first trigger circuit which is applied ,toA thesecond trigger circuit to cause a transfer in conductionv to the secondtrigger circuit to restore it to its starting condition. This latteractionv in turn forreset. v,

It is therefore an object of the present invention to provide animproved reset circuit which npermits a faster reset of an .electroniccounter' than was possibleheretofore. y

It is a further object of the present invention to provide an improvedreset circuit which dissipates pulses generated bythe resettingaction.V

It is still another object ofthe present. invention to provide a new andimproved reset Y.circuit for an electronic counter.

These and furtherl objects. are achieved, in .ac-

cordance with,thepresentinventiom by coupling a diode or, rectier from,the grid of the tube .in

each trigger circuit which it is desired to reset to the cathode of acathode follower tube. vA bias i s n applied to the diodes through the.cathode load.

impedance so, that'there is no interference with the operation of thecounter during a counting interval. Whenreset isdesired, a reset pulseis apv.

plied to the cathode follower andthrough each nection with theaccompanying drawing, which represents a circuit diagram of a preferredem-V bodiment of the invention.

Three stages of a well-known '.binarytypeofg;

counter are shown, each stage consisting otra..V

trigger circuit which is connected to apply a pulse to the subsequenttrigger circuitiafter. it hashad two pulses applied to its input.'

The counter is arranged to be driven by negative pulses. counter, is theone wherein current conductionA is in the right hand tube of.v eachtrigger circuit, as shown by the arrows.

' A negative inputl pulse is applied through a condenser vIIJ to thecathodesjllofthedouble diode I2."V Each of the anodes 'I6 ofthe'double'dio'de I2 are connected to agri'd 24,30 of "each of thetriodes I8," ofthe rtriggercircuitrcomprising the first counterstagefgAgrid1eak`resistor I3 'couples the diode cathodes to ground. Thetriodes I8, 28 have individual load'iresi's'tors 34, 36 connecting eachof theiranode's'26, 32A to a source of 'anode potential. Thelefttriodeanode 28 is connected to the right triode grid 30 through aparallel connected'resstor 38 and '40. The right triode anode 32 is alsocoupledlto the vleft triode grid 24 'by a parallel connected 'resistor42 -conde'nser' 44 "combination. Although' thetrgger circuits are shownas' having triodes,'. multi'grid electron discharge tubes may besubstitutedltherefre in a manner which is well known to thbseskilled inthe art. Each of 'the grids'.24,'3 0`of th'etrides I8, 2B are connectedto a source of negative Ybias through a separate resistor 461148,Y Thetrigger circuit components and th'e applied Abias have their valuesselected so that the trigger circuit has two stable states. Onewithiconducti'o'n in the right triode 20 and the otherwith',.conduction,V in the left triode I8.

The first negative input-pulse is applied through the double diode IZto..both 'grids 24, 30 'of the first trigger circuit tubes. This has noeffect on the left triode IIl'whichfis already.,non-conduct ing. but thenegative pulse causes the righttriode 20 to go to cut-oil'. This causes`a positive pulse toV be generatedat the rightftriodeanode 32 which isapplied to the leftv triode ,grid 24 causing the left triode I8 tobecomecconductive...

The next negative .pulse appliedftn the first trigger circuitthroughlthe double diode I 2 causes a reversal of conduction fromtheleft triedo I8 to the righttriode 20. 'Inbecoming conductive theright triodegenerates. a negative pulse at its anode 32. Besides thispulse being; applied to the.

tion as the first triggerfcircuit. i Each trigger cir-V The zero, orreset conditionof thev Y cuit goes from its initial orzerostateto-.itssecond the succeeding trigger circuit in returning from itssecond stable state back to its zero state. Therefore, one output pulseis received from the third trigger circuit in response to eight pulsesbeing applied to the rst trigger circuit.

If, at any time during?. count, it is desired to resetthe countentoitsrinitial orezero vcondition with conduction in all the right triodes,a positive pulse, also known as a reset pulse, is applied to the righttriode grids 30, 30a, 30h of the counter..:.'1'l1`is.. fhas the effectof causing all the right triodes 20, 20a, 20h being driven from anonconducting V,to a conducting condition, to generate negativepulses.;VTli'ese negative pulses are applied throughtheycoupling condensers anddouble diodes to the subsequent trigger circuit grids andtendI to1opposethe effects of the reset pulse. Thiscauses the counter to be jittery andsome time must be permitted for it to settle down before being usedagain.

These difficulties may be eliminated by coupling to the counter a reset'circuit which is a preferred embodiment ofthe present'invention. Thisincludes a diode or rectifier 50, 50a, 50h for each triode thatis'being; reset. A cathode follower tube 56 is also provided having aload impedance` or resistance 58 connected to itscathode 60." Each'diode cathode 52,' 52a, 52b'isfconnected to the grid lof the triodebeing reset.' In' thisginstance, these are the right grids 30, 30m-3M);4Each diode anode 54, 54a, V54h is connected 'tothe cathode 60of thecathode follower tube. Anegative bias is applied i to the cathodefollower grid62and to the anodes 54; 54a,'54b of thediodes 50;,'50a,50bthrough the load impedance 5B of the cathodelfollower tube 56. Thisserves thepurpose of keeping the anodes4 of therdiodes 50,5021,1150b`negative with respect to their cathodes even when negativepulses are applied to the grids to whichth'e cathodes are connected. Bythis expedientthe reset circuit. does.

not interfere withtheloperation, of the counter wh'ile counting.Effectively a high-impedance is presented tothe grids bythebiaseddiodes.

When it is ,desiredto reset .thecounten a fposif tive or reset pulseisapplied to. the grid B2 of the cathode follower. The lsignaljon .thecathode 50 follows the grid signal v.and.-thus,a positive pulse.V

is applied throughthe-ldiodes,501 `5021, 50h vto Vthe source presentf-a.low impedance pathmto such negative pulses duringthe timeof..app,lication ofv the reset pulse. 'Thenegativepulseswhich could`cause jitter are thereby. dissipated4 without affecting thetriggercircuit stability., The value of the cathode load resistoriofthe.cathodefol-` lower 56 is selected .gto .be lowwhen.compared with the value ofeach.of.. the grid. resistors I3.' I 3a, I 3b connecting, the gridstoground or a vpoint of fixed potentiahorto the.resistor,4646a, 4Gb'through which negative .biasfzis applied to thew grids. The reset period-is thereby considerably shortened to be the. periodof. the duration ofthe reset pulse and the-.counter islavailable for a countimmediatelyafter `the..termination.ofthe reset, pulse. Thus, the .biaseddiodes` maybe considered as,` unilateral ,impedancespresenting.

a high impedance. during.,theLcounting` interval, and. a low impedanceAVduring..the; reset .pulse in, terval. Y

From the foregoing description, it will be readily apparent that animproved reset circuit has been described which provides faster resettime than was heretofore possible. Although a single embodiment of thepresent invention has been shown and described, it should be readilyapparent that many changes may be made in the particular embodimentherein disclosed, and that many other embodiments are possible, allWithin the spirit and scope of the invention. It will also beappreciated, by those skilled in the art, that the embodiment of theinvention herein shown and described may be used with other types of lelectronic counters than binary counters.

It is therefore desired that the foregoing description shall be taken asillustrative and not as limiting.

What is claimed is:

1. A circuit for resetting a chain of trigger circuits of the typewherein each trigger circuit has two stable conditions, one of which isa starting condition, an electron discharge tube having a grid electrodeto which a voltage pulse is applied to reset said trigger circuit to itsstarting condition, and an impedance for coupling said grid electrode toa point of fixed potential, said reset circuit comprising an impedancethe value of which is low when compared with the value of said gridcoupling impedance, a plurality of unilateral yimpedances, each of saidunilateral impedances being coupled between the grid of the tube in eachof said trigger circuits to: which it is desired to apply a reset pulseand said low value impedance, means to apply reset pulses to said lowvalue impedance, and means to apply a bias to said unilateral impedancesthrough said low value impedance to have said unilateral impedances andsaid low value impedance appear to said grids to have an impedance valuewhich is high when compared to said grid coupling impedance and animpedance value which is low during reset.

2. A circuit for resetting a chain of trigger circuits of the typewherein each trigger circuit has two stable conditions one of which is astarting condition and each trigger circuit includes an electrondischarge tube having a grid electrode to which a voltage pulse isapplied to reset said trigger circuit to its starting condition and animpedance for coupling said grid electrode to a point of fixedpotential, said reset circuit comprising an impedance the value of whichis low when compared with the value of said grid coupling impedance, aplurality of rectiers, each of said rectiers being connected between thegrid of a tube in each of said pair of tubes to ywhich it is desired toapply a reset pulse and said low value impedance, means to apply reset`pulses to said low value impedance, and means to apply a bias to saidrectiers to maintain said rectifier-s non-conductive except duringreset.

3. A circuit for resetting a chain of trigger circuits of the typewherein each trigger circuit has two stable conditions one of which is astarting condition, and an electron discharge tube having a gridelectrode to which a voltage pulse is applied to reset said triggercircuit to its starting condition, said reset circuit comprising acathode follower tube upon which reset pulses are impressed, a pluralityof rectiers, each of said rectiers being connected between the grid ofthe tube in each of said pair of tubes to which it is desired to apply areset pulse and the output of said cathode follower, and means to applya bias to said cathode follower to maintain said rectiers non-conductiveexcept during reset.

4. A circuit for resetting a chain of trigger circuits of the typewherein each trigger circuit has two stable conditions, one of which isa starting condition, and an electron. discharge tube having a gridelectrode to which a Voltage pulse is applied to reset said triggercircuit to its starting condition, said reset circuit comprising acathode follower tube having grid, cathode and anode electrodes, a loadimpedance, connectedtc said cathode follower cathode, a plurality ofdiodes each having an anode and a cathode, said diodes anodes beingconnected to said cathode follower cathode, each of said diodes cathodesbeing connected to a grid of the one oi each pair of tubes to which itis-desired to apply a reset pulse, and means to apply a bias to saidcathode follower cathode to maintain said diodes anodes at a lowerpotential level than said diodes cathodes, except during reset.

IGOR. E. GROSDOFF.

REFERENCES CITED The following references are of record in the le ofthis patent:

VUNITED STATES PATENTS Number Name Date 2,403,918 Grosdoff July 16, 19462,493,058 Bliss Jan. 3, 1950 2,519,184 Grosdoif Aug. 15, A1950

